BNR Stage 3 - #'s don't add up.
 

Last year around this time, I had my car tuned and dyno'd to 15PSI on some ported NS twins and I netted ~340RWP from the car(depending on who's correction #s you factor in). Car has 43K miles on it now, still orignal motor so it still has stock ports etc. I was failry happy with the power #'s but my M2 Medium SMIC was simply heat soaking waaay to much when I started boosting. I wanted to modify a few more things and decided to get the thick Apexi GT Spec FMIC. I also purcahsed ported UIM and LIM for the car, replaced the old fuel system with the CJ Motorsports Rails and ID fuel injectors.

In the midst of all this i bought a set of BNR stage3s from Rx7aholic and decided to go ahead and upgrade the twins with better more efficient twins vs going single just yet.

My results were a gain in ~12hp Uncorrected to the wheels from last year to this year, and this is with much better IATs, and more controlled Water temps vs last year. UNcorrected last year I was at 310hp, this year uncorrected I was at 321 and I was running a bit more boost to 17psi. I had plenty of fuel, but no water or meth yet to reduce knock. So here is what I am scratching my head on: Are the stock ports really that restrictive? I saw a friends car with Stock Ports and a GT40 on e85 hit 440RWHP (before a stuck corner seal stopped his tuning session). Granted E85 helps that knock control, but that is a huge difference.

Here is the setup. I would really appreciate any insight you guys could provide. Mod list:

RB dual exaust (potentially restrictive component)
Magnflow Resonated Midpipe
3"downpipe
BNR stage 3 Twins - NS
RichMans ported manifod (gates removed etc)
Ported and Polished LIM & UIM
Greddy Elbow
Apexi GT Spec FMIC
Efini Y pipe, welded shut for after marked BOV
Apexi Cold Air Intake

HKS Ignition Enhancer
CJ Motorsports Fuel rails
ID 725 Primaries 2200 secondaries
PFC

I still have AC/PS and cruise as well :).

No cooling issues, ducting is working really well. Just for some reason, couldn't safely get the power past 321 uncorrected off the superflow dyno.

Thoughts? Car runs strong. I guess I could check compression again as this is still the stock motor at 43K miles, but I have yet to have any issues with warm/cold start etc.

Thanks for any other opinions. I will post dyno charts soon if you want to compare.

Tuner?

Steve Kan

Sorry to hear about your disappointment Dan. I was hoping to make it up there this year but school has slowed me down way too much. Only 1 more month to go and I'm done for good. How do you like the 725/2000 injectors? That's the combo I'm looking at running, I've already got the 725's but nothing installed yet. I might have to bug you later on about how you have everything plumbed.

The injectors are great. The CJ MotorSports Fuelrails are a snap to install, and they will give you great support. They also modified the spacers on the 48mm injectors for the primaries so you wont need all of the extensions for 60mm injector spacing we are used to. It all fits with plenty of clearance and it provides great delivery. IDs are great fuel injectors thus far at least.....


Now if I can just get this power thing figured out.

Out Put from my tune
 

the dyno graph uses a correction number. I will scan it in too.

Compression test?

Silly question, but are you still running the stock fuel pump? I don't see an aftermarket one listed in your mods.

ahh good catch I have a COSMO rewired pump.

Compression test is maybe the only thing I can think of at this point. Motor pulls Extremely hard though...

Read through this thread, it should answer your questions.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/bnr-stage-3-turbos-966671/

Water meth.... Only way to take it to the next level. That or race gas I guess

Out of curiosity, in your testing, what HP numbers did you get to, prior to spraying water meth mix. I know the motor is capable of making more power by pulling timing especially if I am spraying (something I have been thinking about doing regardless) a fuel water mix. Maybe it is time to go ahead and get the system I have been looking at and get it in place.

IIRC Khris had the older style BNRs which just had the larger compressor wheels but all else stock.....

Yes they are Ver 1 of the BNRs, but still worthy of good power #s... I think it simply boils down to stock ports, and no AI means lower power. Add improvements to one or both, and a change can be seen... Perhaps it may be time to send the motor out for porting and enhancements before it pops!! ;)

That's not true, AI hurts your power a little if you just add it and don't turn up the boost, you add it and turn up the boost more then the boost makes you more power. The hp I made with stock twins was without any AI and high boost

So Tom, I have been following your threads, and granted I prolly need to go back and look at everything again, but your motor was streetported ... ah your sig actually states that, so I guess it goes back to my original question. I should be able to hit 375 based on my mods all day on pump gas, so what gives? Even Stage 1 BNRs are capable of this. I just don't understand the 30+ HP delta. And I agree, just spraying for Knock reduction will take out power, but it should allow for more boost and less timing, allowing for more power, Right?

Now I will say, the turbine sound of the BNRs... AWESOME

I'm not sure but you may just need more boost, and AI would be a good idea to have. I did make 368 hp with the stock engine with 21 psi peak and non seq turbos. On that day it also made only 313 hp with 16 psi. The boost makes a big difference. https://www.rx7club.com/showthread.p...&highlight=368

Boost makes all the difference with these turbos, that and water/meth. I'm sure your stock ports are hurting you as well but it shouldn't make that crazy of a difference. If I were you the first thing I'd check is compression, as usually a post about "why didn't I make that much power" is quickly followed by a "my engine blew" post.

I guess it could be the dyno, but even I did my numbers on a Mustang dyno. Unless it was a Dyno Dynamics dyno I can't imagine your power being that much off.

Only other thing I can think of, and I'm basically taking the lords name in vane by saying this in the rx7 world, but every time I hear about a Steve Kan tuned car the numbers always seem to be underwhelming.

[QUOTE=
Only other thing I can think of, and I'm basically taking the lords name in vane by saying this in the rx7 world, but every time I hear about a Steve Kan tuned car the numbers always seem to be underwhelming.[/QUOTE]

But you also don't hear Steve tuned my car and now I need a motor. I think by default he tunes conserative to protect against all the variable the car will encounter off the dyno. Don's numbers were of a superflow dyno. I know the dyno Don tuned on seems conserative against other dynos I have been on.

I will not discredit steve's tuning abilities at all. There is a reason why this car has 43k miles still on the stock motor and running strong. Steve has tuned this car 3+ times over its life span and this thing keeps on taking a beating. I looked up the superflow dyno... Rumor states its a stingy one for pulling out big #'s. Maybe I am just not setting my expectations right.

Time to take it to the track and let the machine do the talking.

You need to lose that Racing Beat muffler, too restrictive. Secondly, timing isn't what's going to make the power difference it's going to be boost.

As far as the water meth we never ran the car without it so I can't help you there. The tune can make a huge difference, I cannot over emphasize that enough.

What afr did he tune it to? AFR makes a big difference in power, I gained 26 hp going from 11.3 to 11.8 afr (with WI). If you are at 11 or high tens afr, you can get some more power out of it, but don't want to lean it out as much without AI.

This is exactly it. We kept it safe. We did get more power out of a leaner run, but no AI and boosting at 18PSI on pump gas for a street car leaves a bit too much to chance. It also didn't help that my wideband sensor was starting to flake out after a couple years of use and 500 miles of SUPER RICH driving to get prepped for the tune. That was frustrating for sure.

I may just go ahead and get the motor ported and run some AI this next coming winter. I am not trying to set any records on stock motor life, but as Rich once advised, it is a LOT cheaper to port and improve a currently solid motor than to wait til something lets go.

On the RB duals... I am torn. The car is subtlely loud right now - or as one of my friends put it, I have the Cadillac of RX7s (PS, AC, Cruise, working Radio, and it doesn't reek of gas and you can have a conversation as you drive down the road, - yet it pulls like a bat out of hell). I know they are restricting, but how much is the question...

So net result, ~350 HP is a nice safe point @17PSI on stock ports and no AI on pump gas. I guess at the end of the day it is just #s. this car is a blast to drive. ;)

How do you have time to post on the forum when theres so much to polish under that hood :>

^hater

:egrin:

^ I swear I saw you on Butterfield Rd couple weeks ago.

Those are pretty low numbers. I'm running BNR S3's, cj rails, ID 725/1000, Supra pump and supporting mods and tuned to 12psi i put down 358 on a mustang dyno.

mustang dynos are one of the highest showing dynos, so hes right on target with yours

uhhh... what?

every mustang i've ever dyno'd on was lower than any other dyno i've been on.

Ya unless there is a bunch of dynos I don't know about that read lower, the mustang dyno is not one of the highest, I'm pretty sure its one of the lowest.

im losing my mind. i was thinking dyno jet and typed mustang :(. this calls for more sleep.

Yea Mustang dyno shows lower number, the low number might have something to do with the older BNR that Rich mentioned?

Haha yeah they don't call them "ego jets" for nothing. Mustang dynos always read lower. Idk if the older bnrs would make that big of a difference though. If stock turbos or 99 specs with the same setup should put out higher numbers than that. I guess it depends on elevation too, but my car was tuned in the mountains of north carolina so I was pretty high.

If the car pulls like a bat out of hell, then leave it alone. Dyno numbers don't mean jack anyway. Go hit the drag strip for some trap speeds or time yourself in the 40 to 140 mph spring, or 60 to 130 etc.

My thoughts exactly....

If you want to know how much power your car is making and if it's operating correctly, including afr's etc. find a reputable shop with a dynojet and do a couple pulls. You can be sure the secondary turbo is coming online as it should and you can see if the car is operating correctly.
Just make sure the hp and torque curves cross at 5250.

^you bring up a good point Chris, that last one is important.

The dyno curve does indeed cross at 5250 for torque and HP.

How can a Hp / Torque curve not cross at 5252 rpm to be exact? That is the conversion factor from torque to Hp. Dynos measure torque and rrpm. Hp = T*rpm/5252

Mine doesn't. :scratch:

http://img3.imageshack.us/img3/7677/mattfg.jpg

Actually your HP and Torque are the same at 5252rpm, both are about 225. There is nothing wrong with your chart or the dyno, it is just the way the graph is scaled.

If you look at your HP & TQ scales they are different. Some dynos automatically change the scaling to make the graph easier to read with the peak hp and tq in the same area of the chart. On the chart above if both sides were scaled from 50-275 the HP and TQ lines would cross at 5252rpm.

Dang,

Sorry...Dong...

Sorry...Dan....I mean Don....;)

What you don`t realize is that you had BNRs already and replaced them with a stock set. :D

On a serious note, and I don`t know how much weight can be taken into account here, but I`d be curious to see your map from the old setup and the new. But I`d also be curious to know what differences there are between the dynos. Not all are created equal so perhaps go back to the original dyno to see if there is any significant difference. What were the weather conditions?

When you say last year, was it last year or when we were all together two years ago?

Opps, didn't even notice that. Thanks for clarifying. IMO, there is something wrong with the chart, there's not enough power. :(

Sorry for the thread jack Dan!

Same Dyno, Same Tuner (steve) with about a 12HP uncorrected gain.

You have a PM...

Not to be rude, but I think that the dyno operator may have fudged those numbers to make you feel good. Twins will NOT make 358whp at 12psi, regardless of how happy the motor is, you're talking a (roughly) 140whp increase for 2psi of boost. BNRs or no BNRs, that just ain't happening.

Ya no way. I stopped by the local mustang dyno shop yesterday and he was telling me how they can change it to make it read higher numbers if they want to.

Thats funny because I just got off another dyno this weekend out here in El Paso, Mustang Dyno, and made 349 on 12psi. I put it on the dyno because i wanted to play with the setting because of the elevation change.

They should.

5252 is the constant, where tq=hp

"We need to get to horsepower, which is 550 foot-pounds per second, using torque (pound-feet) and engine speed (RPM). If we divide the 550 foot-pounds by the 0.10472 radians per second (engine speed), we get 550/0.10472, which equals 5,252.

So if you multiply torque (in pound-feet) by engine speed (in RPM) and divide the product by 5,252, RPM is converted to "radians per second" and you can get from torque to horsepower -- from "pound-feet" to "foot-pounds per second."

Bingo...

So back to my point.... I don't think it is my motor, at 17 paid on bnr twins I made 12hp more uncorrected on the same synopsis at the rear wheels. Whatever that calculates out to is what it is.
Now another question that has come to mind. Does tuning timing on stock ports vs street/bridge ports make a big difference. In everything I read it sounds as if it does, as does having a larger IC etc. I have seen a lot of theory on power discussing. Timing splits, which I understand, but not as much around how and why you would ignite with more or less timing with each rotor. I am a member of chuck westbroks pfc group, now arghx, and I wonder if maybe I need to read on timing theory again. If nothing else to realize my exhuast and stock ports are holding me back.